Serological evidence for chikungunya and Zika virus infections in patients clinically diagnosed as dengue in Northern Sri Lanka

Abstract

Background: Chikungunya (CHIKV), Zika (ZV) and dengue (DENV) viruses are transmitted by Aedes mosquitoes. CHIKV, ZV and DENV infections produce similar clinical features during the early phase of the illness. Disappearance of chikungunya for the last four decades and no reported evidence of Zika fever in Sri Lanka results in the diagnosis of any illnesses resembling dengue as DENV infection in the country.Objectives: This study aimed to test for serological evidence for CHIKV and ZV infections in samples collected from patients suspected of having dengue fever. Methods: Ninety-one sera were tested to determine past exposure to CHIKV and ZV through anti-CHIKV IgG and anti-ZV IgG positivity whilst recent infections were determined through anti-CHIKV IgM and ZV IgM positivity. Recent DENV & CHIKV and DENV & ZV co-infections were detected using anti-DENV IgM & anti-CHIKV IgM positivity and anti-DENV IgM & anti-ZV IgM positivity respectively.Results: Of the 91 patients, 12% and 21.9% had recent and past CHIKV infection respectively, and 1.1% and 19.9% had recent and past exposure to ZV respectively. The overall exposure rate of CHIKV was 34.1% and that of ZV was 20.9%. Of the 91 patients with the clinical diagnosis of dengue, 69.2% had evidence for DENV infection. Nearly 8.8% had DENV and CHIKV co-infection and none of the patients had DENV and ZV co-infection. Of the patients with DENV infection, 14.3% had past SLJID • www. http://sljol.info/index.php/SLJID • Vol. 13, No. 1, April 2023 exposure to CHIKV and 13.2% had past exposure to ZV. Approximately 63% of CHIKV and DENV co-infected patients had past exposure to DENV.Conclusions: Findings of this study show evidence for exposure to CHIKV and ZV in the dengue suspected patients. Most of the clinical features were similar in recent DENV, CHIKV and ZV infections which will contribute to miss CHIKV and ZV infections in dengue endemic resource limited countries where testing for CHIKV and ZV infections are not routinely done.